The present application relates to a 3-dimensional operation input apparatus for operating, for example, a GUI (Graphical User Interface), a control system, a handheld apparatus, and a calibration method.
Pointing devices, particularly a mouse and a touchpad, are used as controllers for GUIs widely used in PCs (Personal Computers). Not just as HIs (Human Interfaces) of PCs as in related art, the GUIs are now starting to be used as an interface for AV equipment and game devices used in living rooms etc. with, for example, televisions as image media. Various pointing devices that a user is capable of operating 3-dimensionally are proposed as controllers for the GUIs of this type (see, for example, Japanese Patent Application Laid-open No. 2001-56743 and Japanese Patent Application Laid-open No. Hei 10-301704; hereinafter, referred to as Patent Documents 1 and 2, respectively).
Patent Document 1 discloses an input apparatus including angular velocity gyroscopes of two axes, that is, two angular velocity sensors. When a user holds the input apparatus in hand and swings it vertically and laterally, for example, the angular velocity sensors detect angular velocities about two orthogonal axes, and a command signal as positional information of a cursor or the like displayed by a display means is generated in accordance with the angular velocities. The command signal is transmitted to a control apparatus, and the control apparatus controls display so that the cursor moves on a screen in response to the command signal.
Patent Document 2 discloses a pen-type input apparatus including three (triaxial) acceleration sensors and three (triaxial) angular velocity sensors (gyro). The pen-type input apparatus calculates movement directions and movement distances thereof by executing various operations based on signals obtained by the three acceleration sensors and three angular velocity sensors.
Incidentally, the input apparatuses of Patent Documents 1 and 2 use gyro sensors and acceleration sensors that detect, instead of directly detecting displacements, inertial amounts using dimensions of displacements obtained by temporally differentiating angular velocities, accelerations, and the like. The angular velocity sensors and the acceleration sensors each output a fluctuation of a potential with respect to a reference potential, that corresponds to a movement of the input apparatus, as a detection signal. Based on the output detection signal, a command signal including, for example, a position, a movement amount, and a movement velocity is generated.
Meanwhile, because the inertial sensors above detect a movement operation of the input apparatus based on the fluctuation of the potential with respect to the reference potential, when the reference potential is deviated, an inconvenience that a cursor moves at a constant velocity or a constant acceleration irrespective of the fact that the input apparatus is stopped is caused. The deviation of the reference potential is caused by, for example, temperature characteristics of piezoelectric devices and analog circuit devices.
To eliminate unintentional movements of the cursor due to the deviation of the reference potential, the reference potential needs to be corrected periodically or unperiodically. For example, U.S. Pat. No. 5,825,350 (hereinafter, referred to as Patent Document 3) discloses a technique in which a reference potential of a gyro sensor is corrected when an output of the gyro sensor is equal to or smaller than a predetermined threshold value.